Some of those though are NOT worth the pay for the amount of work. The pay is ridiculous.

Yes, the pay is low for most of them. I don't use them myself but if you're in need of some money quickly they do in a pinch. And the writing assignments are not hard so you can whip through them pretty fast.

Plus, I have a mix of private clients and content mills I write for. I like that if I see something I want to write, I can do so without worrying where I'll use it and who will buy it. A few months ago, I wrote about 20 articles using keywords of "little black dress" for a content mill in about two hours and it was insanely easy.

There is a lot for never worrying about when you'll be paid, or weird keyword phrases that are hard to include...if I don't like it at a content mill, I don't pick it up, and there's a lot to be said for the convenience of even a low paying content mill.